相转移催化合成4,5-二氢-3-甲基-1-(4-氯-2-氟苯基)-1,2,4-三唑-5(1H)酮的工艺

Technology Research into Preparation of 4,5-dihydro-3-methyl-1-(4-chloro-2-fluorophenyl)-1,2,4-triazol-5-(1H)-one with Phase Transfer Catalysts

[方法]4,5-二氢-3-甲基-1-（4-氯-2-氟苯基）-1,2,4-三唑-5（1H）酮是唑酮草酯的重要中间体。以4-氯-2-氟苯肼为原料,乙酸乙酯为反应溶剂,PEG-1000为相转移催化剂,经过脱水缩合、1,3-偶极加成、氧化脱氢等3步反应,合成4,5-二氢-3-甲基-1-（4-氯-2-氟苯基）-1,2,4-三唑-5（1H）酮。[结果]研究了催化剂种类与用量、溶剂、反应温度、物料配比对反应收率的影响,得到优化后的反应条件：n（乙醛）∶n（氰酸钠）∶n（乙酸）∶n（次氯酸钠）∶n（聚乙二醇-1000）∶（4-氯-2-氟苯肼）为1.80∶1.60∶1.84∶1.60∶0.04∶1.0,反应温度20~25℃。[结论]该工艺原料易得、反应条件温和、操作简单、收率较好,具有良好的工业应用价值。

[Methods] 4,5-dihydro-3-methyl-1-（4-chloro-2-fluorophenyl）-1,2,4-triazol-5-（1H）-one,the key intermediate synthesizing carfentrazone-ethyl,was prepared from 4-chloro-2-fluorophenyl hydrazine as raw material by the reaction of condensation,1,3-dipolar cycloaddition and oxidation in ethyl acetate as solvent.[Results] The effects of PTC,solvent,reaction temperature and reactant ratio on yield of the reaction were investigated.The optimal reaction conditions were determined： reactant ratio is n（CH3CHO）∶n（NaOCN）∶n（CH3COOH）∶n（NaClO））∶n（4-chloro-2-fluorophenyl hydrazine）=1.80∶1.60∶1.84∶1.60∶1.0,and reaction temperature is 20-25 °C.[Conclusions] The procedure is suitable for industrial preparation for its advantages such as abundant raw materials,mild reaction conditions,simple operations and high yields.